Many 2-benzothiazole rubber accelerator compounds are known and some are widely used in the rubber industry. While the compounds are readily prepared according to well-known procedures in a high state of purity, most, if not all, of them deteriorate when exposed to elevated temperatures and/or humid conditions. The deterioration is manifested by a gradual build-up of mercaptobenzothiazyl disulfide (MBTS) resulting in an alteration of the cure characteristics normally exhibited by the accelerator when used in a rubber vulcanizate. Since elevated temperatures and humid conditions are common in the summer months and throughout the warmer areas of the world, it is desirable to find a means for either stopping or retarding this deterioration without destroying the accelerating activity of the compound.